Have any of you see these Six and Eight Wheelers?
Home of the Land Tamer
They offer up to an 80 hp Deutz BF4 Turbo Diesel Engine with hydrostatic drive and speeds up to 45mph on land and 10mph in water with their water prop! Of course I'm sure that has a lot to do with the 33" tall tires but still, that's some impressive speeds.
They also have aluminum frames and seating for 5-10 people.